A. Field of the Invention
The invention relates to a damper mechanism, and particularly a damper mechanism for transmitting torque and damping torsional vibration.
B. Description of the Background Art
A clutch disk assembly used in a clutch of an automotive vehicle generally has clutch engagement and dis-engagement functions and a vibration dampening features. The dampening features typically include absorbing and damping vibrations transmitted from the flywheel.
The clutch disk assembly includes a pair of input plates opposed to each other, an output hub integrally provided with a radially outwardly extending flange, and coil springs elastically coupling the input plates to the output hub in the circumferential direction. The coil springs provide some of the vibration dampening features. The paired input plates are fixed to one another by stop pins at their outer peripheral portions, and therefore can rotate together as a single structure. The stop pins extend through recesses formed at the outer periphery of the flange, respectively. The input plate pair can rotate relative to the flange through a predetermined angle range, and the relative rotation between therebetween is limited by contact between the stop pins and circumferential ends of the recesses. As described above, the stop pins couple the paired input plates together, and also serve to limit relative rotation between the input plates and the flange of the hub.
The stop pin must have a predetermined diameter, and must be arranged radially inside the outer peripheries of the paired input plates. Due to the above requirements, the relative torsion angle between the pair of input plates and the flange cannot be increased beyond a certain angular range in the structure employing the stop pins. This means that the performance of coil springs cannot be fully utilized even if the coil springs have a high strength, because the relative torsion angle cannot be increased sufficiently. For reducing gear noises and muffled noises in a drive system during driving, it is necessary to minimize the torsional rigidity during acceleration and deceleration, and thereby set a torsional resonance frequency of the drive system to a value lower than a service speed range of an engine. For achieving a low torsional rigidity and a high stop torque, it is necessary to ensure a wide range for a low torsion angle.
An object of the invention is to provide a damper mechanism, which allows a sufficiently large torsion angle between an input rotary member and an output rotary member, and thereby can suppress vibrations during driving.